1. Field of the Invention
The present invention relates generally to the technical field of data transmission and, more particularly, to facilitating an addressee's prompt retrieval of faxes from any location anywhere in the world.
2. Description of the Prior Art
There exist two types of on-line collaboration--synchronous and asynchronous. In synchronous collaboration, people exchange information in "real-time" over high speed communication networks. Synchronous collaboration holds the promise of sharing documents, databases, and multi-media information. However this requires significant infrastructure in the form of computer equipment and permanent connection to high speed networks. While the amount of data exchanged during synchronous collaboration may be large, particularly for multi-media transfer, the amount of information maybe limited to words or gestures. Furthermore, a lack of communication standards, computer systems and document formats have delayed widespread implementation of the promised Internet based synchronous collaboration.
In contrast, asynchronous collaboration is more useful when either party does not have access to high speed permanent connections. If large amounts of information are to be exchanged over temporary low speed lines (56 KB), then asynchronous communication is more useful because the data can be exchanged without both parties being connected at the same time. Asynchronous collaboration is also more useful when a large amount of information must be analyzed by either party.
Use of fax communication continues to increase despite parallel growth in electronic mail (email). Despite the explosion in Internet communication, fax communication continues to increase. According to a 1996 Pitney Bowes/Gallup poll, fax is still the preferred method of business communication among both Fortune 500 and mid-sized business users. Davidson Consulting, which estimates that 336 billion pages will be faxed worldwide in 1996, surveyed fax machine end users and dealers and found that fax toner usage on existing machines rose at a 12% annual rate from 1995 to 1996. IDC/Link Resources reports that the computer-based fax market will sustain a 28% compound annual growth rate from 1995 through 1999.
Fax communication continues to grow because it is a universal means of rapid worldwide communication. Any two people with fax machines that are able to communicate telephonically can exchange documents by simply putting a piece of paper in one machine and receiving it as a printed document at the other machine. Availability of direct satellite telecommunications, such as the Iridium network, removes any technological barrier to sending and/or receiving faxes anywhere in the world. Advantages of fax communication are that it is cheap, simple, universal, and format independent. Furthermore, fax communication has an advantage over traditional email in that it conveys an author's graphics and layout in their original format.
A significant disadvantage of present fax communication is that, unless the sender has an addressee's personal fax number, the fax has to be forwarded to the addressee. Forwarding faxes generally requires visual inspection and manual routing to the addressee. Moreover, if a fax addressee's location and telephone number changes frequently, it becomes more likely that they may not receive faxes promptly. In comparison with email, down-loading a fax's image is time consuming over present telephone lines. A fax server, particularly a networked fax server, partially solves the fax routing problem. U.S. Pat. No. 5,461,488 entitled "Computerized Facsimile (FAX) system and Method of Operation" discloses a system that receives a fax, stores the fax in a computer file, performs optical character recognition (OCR) on the stored data to determine the fax's destination, and then uses an email program to route the fax to its destination(s). However, according to an article that appeared in Byte magazine, "Network Fax servers' greatest weakness is in routing received faxes."
Presently, various different fax server systems exist that automatically route a received fax. One approach to automatic fax routing assigns each fax addressee a unique telephone extension number so a fax can be routed beyond the fax server to the addressee's workstation. Senders must know the addressee's entire fax telephone number including extension, and enter the extension number at the proper moment using a TouchTone.RTM. telephone. Sometimes, a voice prompt indicates when to enter the extension number. There are several difficulties with this method. First, the sender must have access to a TouchTone telephone which may not be available to, or widely used by, potential fax senders. Next, the sender must know and dial the addressee's extension number. Moreover, the method doesn't work for automated fax transmissions (delayed sends, auto re-dials--the kind of faxes sent automatically by fax servers). Consequently, fax servers that use an extension number for routing faxes have proven less than satisfactory.
An alternative method for transmitting a code number designating a particular fax addressee employs a modified handshaking protocol between the transmitting fax machine and the fax server. The modified handshaking protocol includes a sub-address which carries the addressee's code number from the transmitting fax machine to the fax server. Equipping fax machines for the modified handshaking protocol requires that they conform with an ITU-T T.33 telephone standard. Presently, fewer than 1% of installed fax machines support any form of sub-addressing, putting in question its applicability in anything other than highly controlled environments.
Yet another approach employed for fax routing assigns each addressee a unique, direct-inward-dialing (DID) telephone number. DID employs the same telephone technology that allows people in large office buildings to have a "direct line." With DID, each workstation has a direct fax phone number, but calls to all the different users' fax phone numbers arrive over a single phone line (or common bank of multiple lines). Receive-only telephone lines for each and every DID telephone number connect either to a single fax server equipped with DID compatible fax boards, to a DID gateway, or to a conversion module. All faxes for assigned telephone numbers arrive over the same DID phone line(s), and the DID system in the fax server matches the seven-digit number to the proper mailbox. Remote senders need only know an addressee's ordinary fax telephone number. The phone company assigns DID numbers (often in packs of 10, 50 or 100), and each user is assigned a fax mailbox corresponding to that user's unique seven-digit telephone number. U.S. Pat. No. 5,287,199 entitled "Facsimile Message Processing and Routing System" discloses such a system in which the unique DID telephone number is also a key for retrieving from a database an information processing record that controls fax processing.
With multi-line fax servers, faxes received on separate telephone lines, each having its own phone number, can be routed automatically to a particular department, and then be either automatically printed, or manually or automatically forwarded from there. For example, if a fax server has four lines, each telephone line can receive faxes for one of four different departments, while all four telephone lines can still be used in a shared mode to handle all outbound faxes. Disadvantages of such systems include incurring monthly charges from the phone company for each DID line, plus potentially substantial installation fees and delays. Sometimes installing DID is complicated or impossible.
Another way to route incoming fax messages places an addressee identifier into the transmit terminal identifier (TTI) message that appears in the top margin of each received fax page. The TTI message identifies the sender, usually with a fax telephone phone number and/or company name. Fax servers can be programmed to recognize a TTI and route all faxes with that TTI to a particular workstation and only that workstation. This makes TTI fax routing suitable for niche applications, e.g., Purchase Orders routed by geographic region to individual addressees.
Currently a number of automatic fax routing systems can route document images based on content. In this method, the document's content is extracted from a pre-defined location on the document's image, and then used in forwarding the document to a person or a location. In theory, this approach can be used for routing faxes automatically. U.S. Pat. No. 5,175,684 entitled "Automatic Text Translation and Routing System" discloses such a system which requires use of a fax cover page having predefined fields. In practice, two problems occur. First, pre-definition of the document proves to restrictive for faxes. There is no fixed fax cover sheet format, and even with a reasonably large set of pre-defined fax formats, errors occur in exact field location and simple translation and rotation of the document image. Secondly, these systems require an exact match with data recognized in the field to route the fax. Current optical character recognition (OCR) has about 2% error per character for good quality documents. On a 15 character name field, this error compounds to a 26.1% error rate of one or more characters. Combination of low fax quality and inherent OCR error make this approach unusable for reliable fax routing.
OCR and/or intelligent character recognition (ICR) may be used for automated inbound fax routing, with some notable caveats. With some OCR-based fax server systems, senders must type the receiver's name in coded format, e.g., &lt;&lt;Peter Davidson&gt;&gt;, and then a properly equipped fax server tries to recognize the code to route the fax. With ICR, handprint can be used for routing, and the fax server can search the entire cover sheet for clues (addressee name, department) used in routing the faxes. However, local area network (LAN) administrators using such systems must maintain a database having all possible fax addressees' names, including nicknames and even common misspellings. Nevertheless, precision of fax routing is quite poor.
The absence of a satisfactorily precise, fully automatic, and backward compatible fax routing technology is a direct consequence of the nature of fax communication. Faxes are analogous to standard business correspondence. It is because of this analogy that fax communication has been so successful in penetrating business communications infrastructures. The ancient and proven business process of written communication via paper was quickly adapted for transmission over telephone lines because the switching costs were low and payoff was immediate. The use of fax machines left the correspondence process essentially unchanged. The envelope, which in paper transmission was used to ensure privacy and routing, has been replaced by the cover page. However, unlike envelopes and their somewhat standard addressing methods, fax cover pages were never standardized. Furthermore, due to the cost of transmission, cover pages are used for message transmission as well as addressing, further frustrating any attempt at standardization.
In contrast to conventional fax communication, email delivers messages to a central mail box from which the addressee can easily retrieve them. Email has three advantages over fax for receiving communications. Received email is editable. Inherently, email is routed automatically to the correct user. Email is available immediately upon logging into the correct email server. However, email looses graphical and format information in the original document. While email can be easily converted to fax, presently there exists no easy way to convert a fax to email.
Converting faxes to email requires extracting fields from faxes which is part of ongoing document analysis research. Document analyses comprises various aspects of understanding contents of paper documents. A significant part of document analysis research investigates decomposing business correspondence, of which fax documents are a subclass, seeking methods for understanding contents of paper documents. Various reports, such as Taylor, et al., Document Classification and Functional Decomposition, 1995 Symposium on Document Image Understanding Technology, p. 56 and Dengel, et al., OfficeMAID--A System for Office Mail Analysis, Interpretation and Delivery, International Association for Pattern Recognition on Document Analyses Systems, 1994, pp. 253-276, describe research into decomposing business letters. Dengel, et al.'s method uses a tree search in attempting to match a geometric layout employed in German business letters with templates. If a letter does not match any template, the template which most closely matches the letter is selected, or the user is given an opportunity to add another template to the list. Dengel, et al. describe experiments attempting to convert business letters into email.
Taylor, et al. in Functional Decomposition of Business Letters, Fourth Annual Symposium on Document Analysis and Information Retrieval, p. 435, describe a more comprehensive method for analyzing business letters. The method uses text cues, format cues, and location cues to identify components of the letters. The method employs a four pass rule based system to successively identify the components. If-then-else like rules identify components in the letters, and then a grammar combines the components into a larger structure. Taylor, et al. report that using fuzzy rules helps in ambiguous situations.